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Title

Zircon Petrochronology of the Meghri-Ordubad Pluton, Lesser Caucasus: Fingerprinting Igneous Processes and Implications for the Exploration of Porphyry Cu-Mo Deposits

Authors
Tayan, Rodrik
Published in Economic geology and the bulletin of the Society of Economic Geologists. 2019, vol. 114, p. 1365-1388
Abstract The trace element composition of zircon, especially in tandem with U-Pb geochronology, has become a powerful tool for tracing magmatic processes associated with the formation of porphyry copper deposits. However, the use of the redox-sensitive Eu and Ce anomalies as a potential mineral exploration proxy is controversial. This study presents a comprehensive, temporally constrained data set of zircon trace element compositions (n = 645) for three compositionally distinct magmatic series identified in the Meghri-Ordubad pluton, southernmost Lesser Caucasus. The 30 million years of Cenozoic magmatism in the Meghri-Ordubad pluton are associated with several ore-forming pulses leading to the formation of porphyry copper deposits and epithermal-style mineralization. Our zircon geochemical data constrain the thermal and chemical evolution of this complex intrusive suite and allow an evaluation of the usefulness of zircon as a mineral exploration proxy for porphyry copper deposits. Our results combined with Rayleigh fractionation modeling indicate that the trace element composition of zircon (Th/U, Hf, Ti, YbN/DyN, Eu anomalies) is influenced by the composition and the water concentration of the parental magma, as well as by co-crystallizing titanite and apatite. In contrast, the variations of Ce anomalies remain difficult to explain by magmatic processes and could rather be ascribed to relative fluctuations of the redox conditions. In the Meghri-Ordubad pluton, we do not observe any systematic patterns between the trace element composition in zircons and the different ore-forming pulses. This questions the reliability of using the trace element composition in zircon as an exploration mineral proxy, and it rather emphasizes that a good knowledge of the entire magmatic evolution of a metallogenic province is required.
Keywords ZirconPetrochronologyLesser CaucasusTethyan beltPorphyry depositsCuMo
Full text
Structures
Research group Mineral Resources and Geofluids
Projects
Swiss National Science Foundation: 200020_138130
Swiss National Science Foundation: 200020_155928
Swiss National Science Foundation: 200020-138130, 200020-155928, and 200020-168996
Autre: SCOPES Joint Research Projects IB7620-118901 and IZ73Z0-128324
Citation
(ISO format)
REZEAU, Hervé et al. Zircon Petrochronology of the Meghri-Ordubad Pluton, Lesser Caucasus: Fingerprinting Igneous Processes and Implications for the Exploration of Porphyry Cu-Mo Deposits. In: Economic Geology, 2019, vol. 114, p. 1365-1388. https://archive-ouverte.unige.ch/unige:121930

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Deposited on : 2019-08-27

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